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authorPavel Skripkin <paskripkin@gmail.com>2021-05-17 15:15:45 +0300
committerJan Kara <jack@suse.cz>2021-05-17 15:07:54 +0200
commita149127be52fa7eaf5b3681a0317a2bbb772d5a9 (patch)
treed7505e39459ffaed87b8e624532268939311a0f2 /fs/reiserfs
parent5b9fedb31e476693c90d8ee040e7d4c51b3e7cc4 (diff)
reiserfs: add check for invalid 1st journal block
syzbot reported divide error in reiserfs. The problem was in incorrect journal 1st block. Syzbot's reproducer manualy generated wrong superblock with incorrect 1st block. In journal_init() wasn't any checks about this particular case. For example, if 1st journal block is before superblock 1st block, it can cause zeroing important superblock members in do_journal_end(). Link: https://lore.kernel.org/r/20210517121545.29645-1-paskripkin@gmail.com Reported-by: syzbot+0ba9909df31c6a36974d@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/reiserfs')
-rw-r--r--fs/reiserfs/journal.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index 9edc8e2b154e..0834b101c316 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -2758,6 +2758,20 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
goto free_and_return;
}
+ /*
+ * Sanity check to see if journal first block is correct.
+ * If journal first block is invalid it can cause
+ * zeroing important superblock members.
+ */
+ if (!SB_ONDISK_JOURNAL_DEVICE(sb) &&
+ SB_ONDISK_JOURNAL_1st_BLOCK(sb) < SB_JOURNAL_1st_RESERVED_BLOCK(sb)) {
+ reiserfs_warning(sb, "journal-1393",
+ "journal 1st super block is invalid: 1st reserved block %d, but actual 1st block is %d",
+ SB_JOURNAL_1st_RESERVED_BLOCK(sb),
+ SB_ONDISK_JOURNAL_1st_BLOCK(sb));
+ goto free_and_return;
+ }
+
if (journal_init_dev(sb, journal, j_dev_name) != 0) {
reiserfs_warning(sb, "sh-462",
"unable to initialize journal device");